Chemical contamination is a critical concern for magnetic recording. As the dimensions of the head-disk interface decrease, ever smaller amounts of contamination can cause it to fail. It is desirable to monitor the internal condition of disk packs in order to facilitate preventive maintenance. In so doing, disk drive failures can be anticipated or avoided by identifying an unacceptable level of contamination. Currently, it is very difficult to monitor the deposition of aerosols and low vapor pressure "environmental" chemicals, such as complex organics emanating from greases, oils, air conditioning systems, gaskets, plastic enclosures, etc. It is presently necessary to open and disassemble a head-disk assembly (HDA) in order to analyze contaminants which settle on the internal surfaces.
Attenuated total reflection (ATR) is a well-known principle in infrared (IR) spectroscopy. A paper entitled "Fourier Transform Infrared Spectra of Organic Compounds in Solution and as Thin Layers Obtained by using an Attenuated Total Internal Reflectance Fiber-Optic Cell", published in Anal. Chem. 1988 at pp. 1908-1910 discloses the use of infrared-transparent optical fibers as an ATR device for measuring the composition of liquids and solids.
No prior art known to applicants, however, teaches an apparatus or method for detecting and measuring airborne surface contaminants by using the ability of thin IR-transparent optical fibers or ATR crystals to trap airborne contaminants in combination with using IR spectroscopy or attenuated total reflection techniques to identify and measure surface deposits as minute as a fraction of a monolayer.
There is a need for a means and method to measure airborne contaminants in situ within a sealed environment especially one containing moving parts, such as a disk file, without interrupting its operation in any way.